This invention relates to a transducer and associated circuitry for producing electrical signals indicative of the position of a control lever. More particularly, this invention relates to a rotary inductive transducer and circuit for generating electrical signals indicative of the position of a speed control lever in a hydrostatic drive system.
A typical hydrostatic drive system includes a variable displacement hydraulic pump or motor controlled by an electro-hydraulic pilot valve, such as described in U.S. Pat. No. 4,229,144 and U.S. Reissue application, Ser. No. 226,574 filed Jan. 19, 1981. In such a hydrostatic drive system, the pilot valve may be activated by signals generated by a potentiometer-type transducer coupled to the speed control lever. Potentiometer-type transducers are vulnerable to electrical fault conditions. For example, a short or open circuit condition in the potentiometer could cause an increase in the magnitude of the signal received by the pilot valve. This could cause a dangerous increase in the power output of the pump without any change in the position of the speed control lever.